Effort starts to head off peach fruit fly

Jul 01, 2006

The California Department of Food and Agriculture (CDFA) has established a 105.5 square-mile quarantine zone including portions of Fresno and Madera counties following the discovery of peach fruit flies (Bactrocera zonata). Since May 15th, six flies have been trapped.

“Exotic fruit flies are a serious threat to California agriculture,” said CDFA Secretary A.G. Kawamura. “The quarantine is a necessary step to keep this infestation from spreading and allow growers to safely market their crops. We are confident in our eradication program, which has a 100 percent success rate against this exotic pest and others like it in California.”

The quarantine area for Fresno and Madera counties includes the initial detection sites as the epicenter and a buffer zone, which extends approximately 4-1/2 miles in each direction from the find sites. The purpose of the quarantine is to closely control and monitor the movement of agricultural crops, backyard fruits and vegetables, soil and other plant materials to prevent the spread of this infestation. Growers in the quarantine area will be required to sign compliance agreements governing the treatment, harvest and movement of their crops.

Under carefully monitored circumstances, growers may be able to harvest and transport their crops within or out of the quarantine area if approved pre- or post-harvest treatments have been performed. Growers are urged to contact the quarantine project office to begin the compliance process and find out if approved treatments are available for specific crops.

Residents of the quarantine area are urged not to move any backyard fruits or vegetables from their property. These items should be consumed or processed (jams, canning, etc.) on site or disposed of using double-bagging.

“We appreciate the cooperation and assistance that the community has given us so far in this project,” said Kawamura. “In a region that is so closely connected to agriculture, the residents are keenly aware of just how serious an infestation can be. We intend to eradicate this infestation as quickly as possible so that the affected growers can get back to the business of feeding California and the world.”

Increased trapping began immediately following the first fly find on May 15. Eradication efforts began on Friday, May 19, in the 25-square-mile core of the quarantine area, in the area surrounding the fly finds.

The eradication process, known as “male annihilation,” relies on a powerful attractant based on the pheromone that the female fly emits to attract mates. “Bait stations” including the pheromone and the pesticide dibrom are applied 8-12 feet high on utility poles and tree trunks. Male flies are drawn to the stations and die upon consuming the mixture.

The bait stations will be reapplied approximately every 10-14 days for a minimum of two months. The applications could be extended if additional flies are found.

Male annihilation projects have been used several times in California to eradicate infestations of this and similar fruit flies. All of these eradication projects have been successful.

The peach fruit fly is native to parts of Asia including India, Egypt, Thailand, Pakistan, Vietnam, the Phillipines and Taiwan. Crop damage occurs when an adult female fly lays eggs in fruits and vegetables, with the resulting larvae making the produce unfit for consumption.

Homeowners and visitors are urged not to remove fruits and vegetables from the area.